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Old Feb 28, 2014, 05:23 PM
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Build Log
Black Horse Models PZL-104 Wilga

PZL-104 Wilga
Item code: BH124

SPECIFICATION
Wingspan: 2,240 mm 88.19 in.
Length: 1,625 mm 63.98 in.
Weight: 6.4 kg 14.08 lbs.
Parts listing required (not included).
Engine: 26 – 35cc Gas
Radio: 08 channels
Servo: 09 Standard high torque servos.

ALL BALSA – PLY WOOD CONSTRUCTION.
COVERED WITH ORACOVER.

Instruction Manual






Back in 2012 EcomRC had just released an 89” version of the Wilga and that caught my interest. I started reading up on the few build threads that were starting to pop up but got the impression that it didn't do too well, and that was a letdown- I had high hopes for a Good STOL performer. I was aware that Black Horse was also coming out with their version later in 2013 and I contacted Hobby People, Pioneer American (supposed dist for BH in the US) , Airshow RC and even Black Horse themselves to inquire as to when it would be available. All of them responded that they would NOT be importing this model to the US. -I was disappointed to say the least.

Skip ahead a little (like January of 2014) and while surfing I stumbled across (by accident) a couple of build threads in Europe on the Black Horse Wilga (thank you Google for your translation on one of them). To my suprise the authors reported that it had exceeded their expectations and they seemed to like it. Even though both were IC powered, it definitely got me thinking about the Wilga again-especially when one contributor to the thread ordered the plane from Germany and had it sent all the way to New Zealand!

Needless to say that was all I needed to push me over the edge and I had one ordered and on its way from the same shop. Shipping was not cheap by any means, and there was a period I almost lost hope of ever receiving it (USPS and Weather), but my luck held out and although the box had obviously been soaked, neglected and compressed, the plane inside was unharmed (whew!).

**update** here is one on RCAEROTOWING that just started as well. (28 Feb 2014)


So enough talk, let’s begin:

The unboxing has no pictures as I was not thinking of writing this at the time, but it was uneventful. Double boxed, everything wrapped and tied down snug for transport. As I mentioned, the box had water damage and was compressed at one end about 4 inches but the contents were A-OK. I also started assembly, but I will go back and take pictures of how I did things.




Here you can see the fuse sitting on my workbench. I have been test fitting the wing tube and also temporarily running some servo wires.


Since I will be electrifying this, obviously mods will have to be done. Earlier in 2013, I had thought about buying the new 1/4 scale Super Cub from Hangar 9 and even went so far as to order the interior kit, a motor/esc I wanted to use, a Morgan Mill Motorbox and battery tray for it. I decided not to get the Cub but still had the parts for it, so while contemplating the purchase of the Wilga, I did some calculations to see if the cub motor would work for this - in a word: Yes!

This is what I will be powering the Wilga with:


MOTROLFLY DM-5320-330KV

Phoenix Ice 75

ZIPPY Compact 4000mAh 8S 25C Lipo Pack

Biela 19x7 Wilga 2-Blade Carbon Fiber Propeller, Silver with Yellow Tips (neat!)





Powerplant:

I have to say that I am very happy with how my powerplant and battery selection turned out. It was by blind luck actually...The motor was a no-brainer, I knew that would work; it was the prop and the battery location that had me concerned. The BH Wilga has a lot of scale features and a unique way of hiding all the radio bits. The fuel tank sits under a panel, completely hidden from view and I was worried that the 8S battery I wanted to use would not fit. I ordered the Zippy Compact for that reason (that, and it was on sale) but my fears were unfounded. I can actually fit two 8S 4000mAh packs side by side with no issues, and I have to say that was a tremendous bonus should I need the weight for C/G! The Prop is specifically made for Wilgas by Biela and is very well made. It balanced with just a drop of CA on the backside of the left blade and looks very much the part on the nose of the plane. I did bench run the power plant to verify everything was working and was pulling over 1KW at around 40 amps at half throttle, so I don’t think I’ll have any issues in that department! I didn’t run it up full throttle, because the battery was at storage voltage and I was too lazy to charge it at the time.




Since the Full scale Wilga has a radial up front, the nose is very short. BH did provide engine standoffs for the IC buffs, but they are nowhere near long enough for the Electric motor I am using.


I really didn't want to run stand-offs that long and thought about ordering the GP large motor mount, but the Motrofly motor I am using just didn't lend itself to that type of mounting. It could be done mind you, but there was a better, and much easier solution. Remember the Morgan Mills Eflite 160 mount I ordered for the Cub? Since I had it lying around with the Motrofly Motor, I wondered if I just couldn't mount that to the firewall of the Wilga and then add some small nylon standoffs to adjust the spacing. Since I had nothing to lose by trying, I dry fitted the Motor Mount together and temporarily mounted it to the firewall and then attached the motor. Guess what, it was a perfect fit! Man that was a nice surprise! Now if I have to bring the batteries further up for C/G reasons, I can just cut the firewall open and have the batteries go further into the box -sweet!



Here you can see the sequence of putting the battery in.




I still have a lot of modifications to do in the battery area, as I want to install an easy to reach arming plug. These photos are of me just checking the fitting of everything. I also will have to wait until I get the rest of the plane together before I do any mods to the firewall, I don't want to cut anything until I figure out my C/G requirements.


Receiver and Servos:

Channel requirements: (not in receiver pin order)

1 Throttle
2 Rudder
3 Tail wheel
4 Elevators
5 Right Ale
6 Right Flap
7 Left Ale
8 Left Flap
9 Tow release

I'll be using the 9 channel JR 921 for control. Here is why: the BH Wilga has a strange rudder/tail wheel setup as that it uses two servos: One pull/pull servo setup for the tail wheel and one single rod setup for the rudder. The pull/pull sits in the middle of the servo tray and the rudder to the left of it. I could use a Y-cable on them to control both and get it down to 8 channels, but I don't have an 8 channel receiver and I do have a 9 channel. I also could put the flaps on a Y-cable and use a 7 channels RX, but meh-I never liked using Y-cables for anything when I don't have to, so 9 Channel it is. (I'll be using a JR 9503 for the TX). The wiring for the wings will be with HD servo cabling going through a MPX connector to the Fuselage.



Here is the servo area for the Rudder, Elevator and tail wheel

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Old Feb 28, 2014, 05:24 PM
One cell short of a Pack
steve1814's Avatar
Good ole Smithsburg, MD
Joined Mar 2007
1,908 Posts
The Wings:


The slat is built into the wing which is really nice and you can actually see that the designers actually tried to mimic the real mechanics of slats where the incoming air is compressed and accelerated over the top of the airfoil thusly allowing the wing to maintain lift at lower airspeed-we’ll see how it works in real life though…


As you can see, the wing tip has the scale housing for the nav lights, just wish they wouldn't have glued them on already, would have liked to actually install some working lights in them.



The Flaps are actually longer than the ailerons, just like the full scale, and also airfoiled just like the full sized. The hinges are phenolic (some call it G10 FR4) on a common hinge pin that you can actually remove via the fuse side of the flap. I pulled the starboard wing control surfaces off to shrink down the covering a bit (which I will have to do quite a bit of on this bird) and it was easy to remove the wire. Reattaching the surfaces was almost as easy, just need a little patience.




The installation of the wing servos was a pretty standard affair; I used Hitec HS-485’s on the flaps and Power HD DS090M’s for the ailerons. The Power HD’s were a tad too big to fit the servo mount, but a couple swipes with a sanding block cured that issue.







The servo horns were also phenolic, and I drilled some holes in the lower tabs to give the epoxy something to flow through. I did this on all the control horns.










I like using the multiplex plugs for wings. I use a recessed mount for the fuse side and just let the wing side hang free. It makes plugging in the wings fool proof and very easy to do. Here you can see the plug for the wing I just completed. I combine the +/- of each servo on the wing side and just run a 4-wire servo wire to the receiver on the fuse side to cut down on clutter.





Another little bonus discovered was the tab mount for the flap control horn. The default setup allows you to use your flaps servos on a Y-cable, where you have to have both servos mounted and operating in the same direction. Since I am running the servos on separate channels, I will reverse one servo and it will be a mirror of the other servo, just like the ailerons are. My method would require me to re-position the control horn on the control surface and also “flip” the servo horizontally. Usually this means adding another slot to the flap surface, but not on this model-there is a slot for both methods of use. The non-y cable version slot is covered over, but a quick cut with the xacto knife and viola new slot. I just used a snip of covering from exposing the servo mount hole to cover the y-cable slot.





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Old Feb 28, 2014, 05:24 PM
One cell short of a Pack
steve1814's Avatar
Good ole Smithsburg, MD
Joined Mar 2007
1,908 Posts
Wing servo wires

With the wing wring done it was time to move on to routing the wiring through the fuselage. I ran an extra servo lead up to the top of the cabin (not pictured) for the tow release of which I have yet to install




I routed the servo wire down the bulkhead and hot-glued the wire into place



Then I installed a balsa "L" shaped cover to hide the wiring



Then I painted the new cover with Testors flat Gray to blend it in to the rest of the interior



With the floor back in place



The Receiver

The receiver mounting was pretty straight forward. I decided to mount the receiver toward the rear of the plane to keep it away from the batteries. I am going to be working on a anti-spark arming plug and I need the space up toward the front where the batteries are to keep the wiring short as possible. Also, with the constant removal/installation of the flight batteries I wanted to keep from disturbing the receiver wiring in the process.

Here are a few shots of the receiver and the satellite mounting locations:







Servo Mounting

With the receiver in it was time to move on to the servos. Again, pretty straight forwards with the exception of the Pull/Pull for the tail wheel.


As you can see in the photos below, the tail wheel has its own servo.




I decided to put the tail wheel springs close to the servo so they don't snag anything. usually you have the springs on the tail wheel, but I prefer to do it the way I have it. The Wilga has no spring on the tail wheel cable, so all the better




Landing Gear

With that done, it was on to the main landing gear....I need to insert some more pictures of the fiddy bits, but here are a couple of how the main gear fastens to the fuselage.

The main gear is screwed down in the holes provided. there are blind nuts on the other side, but you can access them in case you need to replace one from the interior



The first piece of the L/G filet is slipped over the gear prior to screwing it down and then glued to the fuse once the mains are fastened. The Maual says to use CA, I will use clear silicone so if I have to remove the gear, the filet will come off easier.



What is not shown (will update later) are the cripple struts that mount to the mains. They were a pain to adjust and the instructions are very vague, but common sense will get you through the installation.

The Wheels for the mains are a little small and make the plane look anemic. I love the look of cub wheels and usually replace all my wheel with cub type ones. The Wilga will be no different!

Here you can see the Stock wheels



How they mount



and what they look like on the plane (yuck)




Now enter the cub wheels




How they mount




and how they look on the plane (much better)




I will have to add a longer spacer for the cub wheels as they are thicker and will rub on the mains if not spaced correctly.

Now on to the tail wheel...

The tail wheel looked flimsy in my opinion and it made the plane sit too low in the rear.

The provided tail wheel



How it sits low




A while back I ordered this nice tail wheel from Bangood for a real cheap price and figured I would use it on something...Just so happened, the Wilga is the "something" I am going to use it on!


Still in wrapper. I think I paid $2.00 for it





The back two holes lined up perfect with the original, it was just too long, so a hacksaw got it to the size I needed. I will paint this red once I get a color match.





Now this is MUCH better! I may even add a fake shock absorber on the tail wheel





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Old Feb 28, 2014, 05:25 PM
One cell short of a Pack
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Good ole Smithsburg, MD
Joined Mar 2007
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The Motor Compartment

Building the cowl Ring

The cowl is supposed to anchor on 3 points, two on the side of the firewall and one on top. I didn't like that as it didn't give enough strength to the large cowl so I started to build a cowl ring.

The way the cowl is shaped precluded me from making a one piece ring. Instead I had to break it up into two pieces to get a good fit. the upper part of the cowl seems to be reinforced more, so I concentrated in getting the bottom sturdy and just made the top piece to help shape the cowl.

Tracing the upper part of the cowl was easy, but doing the bottom was a real exercise. There was not reference to go by as the cowl would distort any time I attempted to trace it. I wound up finding a bucket top and traced the circle on cardboard and adjusted from there



Update 28 March 2014



Once I had the basic form done (with a LOT of trial fitting a sanding!) I next had to build a frame for the lower piece to fasten to.



After fitting the pieces together, I then started to drill air holes. These holes are not for lightening the wood, but to provide an exit for the air coming in from the front.



With the cowl mounted you can see just how well everything fits.




I still have yet to put the mounting blocks on the cowl ring, that will come after I get the motor mount finalized. And I also have to paint the ring. The inside will be grey like the firewall and the outside will be black.



Here is what it looks like with the cowl temporarily in place.


Best laid schemes of Mice and Men......

(21 Mar 2014) Don't you just love it when things don't go as planned? as I posted below I decided to see what my C/G was looking like.....

Ugh, I am WAY off C/G with the batteries in the old fuel tank location

So, to get the C/G close to the recommended position, I am going to have to build two battery trays in front of the firewall. I mocked up what might work, but didn't take any pictures at the time as I was kinda mad that was going to have to go this route. Today, I built the trays:



you can't tell from the pictures, but the underside of the trays are reinforced with spreaders and it is also attached to the motor box extension.




The batteries fit quite snug and although you see the velcro around the packs, I am not going to use that particular velcro. I will be using a type that you can really snug up the batteries with, I just haven't installed it yet.







To verify that I am on the right track, I did put the wings on and checked the C/G. As you can tell below, she is sitting almost level and once the prop and cowl are on, she should be spot on.



I will be using the prop shaft as my guide for being level. Once the shaft is parallel to the ground I'll consider her balanced. She is sitting at 14lbs, 10 ozs right now, so I think I am in good shape.


To keep from having to remove the prop and cowl to get to the batteries I am also going to have to cut the top of the cowl and make a hatch. This is where the pucker factor starts, since I can't get a replacement cowl very easily if i mess up.
I am going to build the rest of the plane-probably even maiden it and then I'll attempt the hatch.


UPDATE 28 MAR 2014

Just an update on the finished battery tray. I did some scroll work on the upper cowl ring to get rid of some wood that was unnecessary and then painted everything except for the front of the MM box extension. I still need to do some finishing on that by adding a spacer, so pay no attention to the basswood slats behind the motor mount-they are just placeholders




I also got some smaller 8S batteries. The combined weigh savings was 10.5 ounces and I lost 1400mAh in capacity. The weight saving was just about a wash with the missing cowl, prop and prop nut that was not installed when I did the C/G check. I now have a lot of room to move the RX Battery (2300mAh A123's) around to tweak things a bit. I may run the 4000's to see if the plane flies well with added weight.

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Old Feb 28, 2014, 05:25 PM
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Good ole Smithsburg, MD
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THE ANTI SPARK

One thing I always hated about big electrics was plugging in the batteries. Even with an arming plug, the caps charging on the ESC was enough to arc the deans plug and score nice gouges in them (arc welding eh?) Last year I made my first arming plug with an anti spark feature using a 10Ω, 5 watt resistor for a 12S jenny I loved to fly. It worked well, but was a pain because of the way I made it required you to connect two different leads. Then I stumbled on Jeti's answer to the problem., combining the arming plug with the anti-spark in the same 5.5mm bullet. I wont go into too much detail, but it was the solution I was looking for. I have incorporated the setup in the Wilga as seen below.

Here are the pilots for the plane. there is a niffy set of cup holders that I though would be perfect to hide the arming plug in





I reamed out the bottoms of the cup holders and made a stiffening brace for the plastic (it is thin)



Then I made a holder for the connectors that was spaced correctly for the cup holders. Here you can see the SMD resistors that Jeti uses.



Then it was temp fitted to the underside as well



Perfect fit. The SMD connector is actually the same diameter as the inside of the rear cup holder!



Once that was fitted, I modified a couple of XT deans to jumper the negative leads and connect the positives to the two 5.5 barrel connectors, then built a housing for them and filled it with epoxy.



One that was done, I fitted the floor to the fuselage and plugged it in.



To make it easy to get to the arming plug, I modified the co-pilot's seat with magnets to make removal easy. The seat slides into a lip on the cup holder side, the magnets are there to ensure he doesn't slide out.





The Pilot will not be removed to arm the plane so he gets screwed in place.



The Co-Pilot sits in the back while the plane is "disarmed" That way, a quick glance will let me know power is disconnected. You'll also note that he has the Red shirt-to denote power!



To arm the plane, You just insert the jumper into the front connector first





Then plug in the back (with no spark!)



Then seat the connector all the way in, volia





Once the plane is armed, the Co-Pilot joins the pilot up front.
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Old Mar 04, 2014, 09:48 PM
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Little version

I got the little hk foam version which is surprisingly true to scale and it flies great but....I WANT ONE LIKE YOURS! CMP has them here but they"re out of stock. I'll find one. Be sure to build in plenty of down thrust!
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Old Mar 04, 2014, 11:23 PM
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Did you read somewhere that this model needs down thrust? Just curious.
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Old Mar 05, 2014, 12:06 AM
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down thrust

Actually, no. My little one came with so much that it looked odd and when I took it out it didn't fly nearly as well. The scale is so good on the little one I thought it might be inherent but it could be an idiosyncrasy of this particular model. I'll research it and let you know. From the looks of your pictures it would appear Black Horse knows what they are doing. Is the quality up close as good as it looks in the pics?
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Old Mar 05, 2014, 12:11 AM
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Good ole Smithsburg, MD
Joined Mar 2007
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Yeah, it is a nice model. The only thing that is a hassle is the covering. It is oracover (ultracote) and really needs a good ironing all over. Other than that, it was very well thought out. You'll see more as I progress.

Cheers,
Steve
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Old Mar 05, 2014, 12:28 AM
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Down thrust

I found a thread on down thrust for the pzl but it was inconsequential. It mostly dealt with towing issues.How did they construct the corrugation on the fuselage?
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Old Mar 05, 2014, 12:44 AM
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Good ole Smithsburg, MD
Joined Mar 2007
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Quote:
Originally Posted by mark l View Post
I found a thread on down thrust for the pzl but it was inconsequential. It mostly dealt with towing issues.How did they construct the corrugation on the fuselage?

The Balsa sides of the Fuse has tab holes to accept the corrugated pieces. If I get a chance, I'll snap a picture of the inside of the fuselage sides where the corrugations are so you can get a better idea. The pieces themselves are made of heavy plastic and are firmly mounted. They can deal with the heat from a heat gun well. I have been tightening up the covering on the fuselage with a gun, not an iron and have had to get pretty close to them and they didn't get soft from the heat - not that I directly aimed the gun at them mind you. I was worried that they might be an issue with the covering, but so far, no worries. Putting the registration numbers over the corrugations might prove to be a challenge though....
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Old Mar 05, 2014, 10:38 AM
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Field

You got a grass field out there in MD?
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Old Mar 05, 2014, 10:57 AM
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Quote:
Originally Posted by mark l View Post
You got a grass field out there in MD?
Yeah, nice little field called Pegasus. Our web page looks like we all fly IMAC birds, but the banner pic was during our IMAC event. Our Facebook page has an aerial pic of the flightline and if you click on the photos link you can see a bunch more.

I'm setting up the Wilga to tow sailplanes as we have a bunch of em out there. I am putting better tires on it, as you will see
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Old Mar 05, 2014, 12:43 PM
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grass

Not only do we not have grass here, I've never even flown off it. Nice looking field. It's been a hard winter out there....in fact you just got or are getting snow now, aren't you? You must look forward to spring. Sure would like it for a quarter scale GeeBee R-1 I'm getting close to finishing.
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Old Mar 05, 2014, 08:56 PM
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United States, WA, Sumner
Joined Oct 2000
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Sub'd!

You're killin me Steve!

Perry
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